There are exactly two "tanks" (they actually aren't tanks) in the game with a sight range of 40, the Jackson and the Jagdpanzer IV, all other vehicles of a similar role have less (scouting vehicles are of course exempted from that comparison). The only vehicles to have a higher gun range than the Jackson's 60 are the Elefant and the ISU-152 (both sitting at 70). In fact, the Ostheer's only anti-armour vehicle to have a gun range of more than 50 is the Elefant.
Incorrect.
JPIV is 45 sight range. Jackson gets 45 at vet 2 (although other vehicles get sight as vet as well)
Command PV has 50 sight range at vet 0. Same with Tiger Ace at 50.
British cheats it with the tank commander (non brainer upgrade).
Jadgtiger has 85 range. KV2 on indirect has 70 (IIRC).
OKW both variants of Panther can get/give +5 range with vet.
This is an extra, but there are some skillshots which surpass the basic attack range of the main gun. Same with certain abilities (Combined arms or hulldown).
Anyways, the Jackson extra 10 sight range is only meant to avoid been "flanked".
Regarding the Pershing:
It probably sees less use, the higher the amount of players involved. On the same way JT are not meant for 1v1, the Pershing is probably not a tank for 4v4. I think the tanks is fine.
Some people might want an improved health pool (800 to 960) but i think AoE should be tweaked if that's the case.